a) Field of the Invention
The invention relates to a dispensing apparatus for use with twin cartridges that have two axially parallel storage cylinders and a nozzle piece connecting them; the dispensing apparatus has two plungers, one for each storage cylinder, which are guided to move longitudinally at a predetermined axial distance, and a holder for interchangeable cartridges, which has a guide for the nozzle piece of the cartridge.
b) Prior Art
The twin cartridges intended for use with the dispensing apparatus serve in a known manner for processing so-called two-component material. They consist of two storage cylinders which contain the components separately from each other, and a transport piston which closes the end of each cylinder opposite the nozzle. For use, a twin cartridge is inserted in the holder of the apparatus. Parallel motion or stroke of the two plungers of the apparatus exerts pressure on the transport pistons which are being advanced correspondingly, and this causes a given volume of the contents of each cylinder to be dispensed. The dispensed volume is determined by the cross-section of the cylinder and the stroke of the piston. U.S. Pat. No. 4,911,328 describes an example of such a dispensing apparatus and U.S. Pat. No. 4,981,241 describes an example of a twin cartridge of the kind referred to.
To ensure that the cartridges work properly, their cylinders must be aligned with the two plungers within the holder, i.e. the axes of the cylinders should coincide as nearly as possible with the axes of the plungers. This does not create any special difficulty as long as only cartridges are used in which the cylinders have always the same diameter; most twin cartridges used to date have generally had two identical cylinders for a 1:1 mixing ratio of the two components. However, some two-component systems need a different mixing ratio of their components and thus require twin cartridges of different cylinder cross-section or diameter.